What is it?
Hydrogen gas is compressed and injected via wells into subsurface formations. Apart from pure hydrogen, there are also options to store natural gas that is lean in hydrogen, or rich hydrogen mixtures with methane, carbon dioxide and carbon monoxide (syngas or town gas). This parallels the underground storage of natural gas, which is used extensively around the world, including in Australia. The options for subsurface storage include salt caverns (which are excavated and shaped by injecting fresh water into existing rock salt formations), depleted gas or oil fields, or saline aquifers. The hydrogen is then extracted back from the formation via the wells when required.
Why is it important?
The underground storage approach allows large volumes of hydrogen to be stored and therefore potentially cope with seasonal variation in demand, not just peak load cycling. Subsurface storage will have much lower costs per mass of hydrogen stored than options at the surface, as it makes use of existing formations and is much safer.
- Gravimetric hydrogen density: ~100% (not taking into account underground cavern mass)
- Storage conditions: High pressure (~50-200 bar) and moderate temperature (30-80°C)
- High volume at lower pressure and cost
- Allows seasonal storage as well as peak load
- Very large feasible scale of storage
- Cannot be used for transport of hydrogen
- Specific geological requirements
- Note: The TRL of hydrogen storage in underground formations varies depending on the local geology. Pure hydrogen storage in salt cavern storage is already commercial but not widespread (TRL 8). Storage in depleted fields and saline aquifers has been done for some hydrogen mixtures but needs development (TRL 5)
- Develop methodology for assessing sites
- Develop simulation technology for subsurface mixtures of hydrogen and other gases.
- Identify candidate sites for storage near hydrogen production
- Investigate potential interactions of hydrogen with rocks, fluid and subsurface bacteria
Known active organisations
- CSIRO (related CO2 and natural gas storage research)
- Curtin University
- The Future Fuels Cooperative Research Centre
- The University of Melbourne